From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Mon, 9 Nov 2020 18:41:05 +0000 (-0500)
Subject: mm/mmap: Call __do_munmap() on slow path of do_brk_munmap()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a5d829b2577adef842bf39d5945d4cb177a61ae9;p=users%2Fjedix%2Flinux-maple.git

mm/mmap: Call __do_munmap() on slow path of do_brk_munmap()

do_brk_munmap() would not handle the unmapping of multiple VMAs in the case of
mprotect'ed regions of a brk() so just use the full __do_munmap() in these
rare cases.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---

diff --git a/mm/mmap.c b/mm/mmap.c
index 3e2094ed8da9..b60891d00fc8 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1842,13 +1842,10 @@ static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
 	if (length < info->length)
 		return -ENOMEM;
 
-	rcu_read_lock();
 	if (mas_get_empty_area(&mas, info->low_limit, info->high_limit - 1,
 				  length)) {
-		rcu_read_unlock();
 		return -ENOMEM;
 	}
-	rcu_read_unlock();
 	gap = mas.index;
 	gap += (info->align_offset - gap) & info->align_mask;
 	return gap;
@@ -1873,13 +1870,10 @@ static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
 	if (length < info->length)
 		return -ENOMEM;
 
-	rcu_read_lock();
 	if (mas_get_empty_area_rev(&mas, info->low_limit, info->high_limit,
 				length)) {
-		rcu_read_unlock();
 		return -ENOMEM;
 	}
-	rcu_read_unlock();
 	gap = (mas.index + info->align_mask) & ~info->align_mask;
 	gap -= info->align_offset & info->align_mask;
 	return gap;
@@ -2839,6 +2833,7 @@ out:
 
 /*
  * bkr_munmap() - Unmap a parital vma.
+ * @mas: The maple tree state.
  * @vma: The vma to be modified
  * @newbrk: the start of the address to unmap
  * @oldbrk: The end of the address to unmap
@@ -2859,42 +2854,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 	arch_unmap(mm, newbrk, oldbrk);
 
 	if (vma->vm_start >= newbrk) { // remove entire mapping.
-		struct vm_area_struct *prev, *next;
-
-
-		ret = userfaultfd_unmap_prep(&unmap, newbrk, oldbrk, uf);
-		if (ret)
-			return ret;
-
-		if (mm->locked_vm)
-			unlock_range(vma, oldbrk);
-
-		mas->index = vma->vm_start;
-		mas->last = vma->vm_end - 1;
-		if (mas_store_gfp(mas, NULL, GFP_KERNEL))
-			goto mas_store_fail;
-
-		/* TODO: Drop linked list */
-		prev = vma->vm_prev;
-		next = vma->vm_next;
-		if (prev) {
-			prev->vm_next = next;
-			if (prev->vm_flags & VM_GROWSUP)
-				ret = 0;
-		}
-		if (next) {
-			next->vm_prev = prev;
-			if (next->vm_flags & VM_GROWSDOWN)
-				ret = 0;
-		}
-
-		vmacache_invalidate(mm);
-		if (ret)
-			mmap_write_downgrade(mm);
-
-		unmap_region(mm, vma, prev, newbrk, oldbrk);
-		/* Fix up all other VM information */
-		remove_vma_list(mm, vma);
+		ret = __do_munmap(mm, newbrk, oldbrk - newbrk, &uf, true);
 		goto munmap_full_vma;
 	}
 
@@ -2927,7 +2887,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 
 munmap_full_vma:
 	validate_mm_mt(mm);
-	return 1;
+	return ret;
 
 mas_store_fail:
 	vma->vm_end = oldbrk;
@@ -2936,6 +2896,7 @@ mas_store_fail:
 
 /*
  * do_brk_flags() - Increase the brk vma if the flags match.
+ * @mas: The maple tree state.
  * @addr: The start address
  * @len: The length of the increase
  * @vma: The vma,